Staying Cool

Consider size and efficiency for room air conditioners

By Brian Sloboda

When shopping, look for Energy Star labels on room air conditioners.

Cooling generally is the largest energy expense homeowners face during the summer. A room air conditioner may seem like an easy-to-install, low-cost way to add comfort, but it's easy to waste energy and money in the process if you aren't careful.

A room air conditioner is an encased assembly — a self-contained box, basically — designed to be mounted in a window, through a wall, or as a console. These units deliver conditioned air to an enclosed space or zone.

Costing between $100 and $1,000, room air conditioners tend to last a long time with minimal maintenance, so selecting the right model can save significant amounts of energy.

Room air conditioners rated by Energy Star, a program run by the U.S. Environmental Protection Agency and U.S. Department of Energy, deliver the same or better performance and use 10 percent less energy on average than comparable models. An energy efficiency ratio (EER) — the ratio of the cooling capacity in British thermal units (Btu) per hour to the power input (in watts) — measures each unit's efficiency. The higher the EER, the more efficient the air conditioner will be. National appliance standards require room air conditioners built after January 1, 1990, to have a minimum EER of 8.0 or greater.

Consumers should look for room air conditioners with timers and programmable thermostats. These features offer better temperature control, allowing users to cool spaces according to their preferences. For example, you can set the unit to turn on 20 minutes before bedtime to make your bedroom comfortable.

Yearly Savings

Energy Star–qualified appliances boast advanced compressors, drawing more heat efficiently from the air. These appliances also use less energy to circulate air and run more quietly. However, they do cost slightly more.

Nationally, an average consumer saves approximately 76 kilowatt-hours per year — about $8 — with an Energy Star-rated room air conditioner. Residents in hot and humid states such as North Carolina could save up to $30 annually. Over the life of the appliance a consumer could save between $50 and $250, depending on the model and climate.

Installing a room air conditioner is typically an easy job. Most can be fit into a window in a matter of minutes. Another option is to create a custom opening in a wall.

Large-capacity units often require a dedicated electric circuit or may have specific wiring and breaker requirements. They may need to be installed by a professional.

Room air conditioners come in a variety of sizes. Many people buy the largest one they can afford, assuming more power is better. But a too-large unit will cool a room too quickly to properly remove humidity, leaving the space feeling cool but also wet and clammy.

Most room air conditioner purchases are "impulse buys"— bought during hot weather by consumers who have conducted little research. Most retail displays do not promote the benefits of Energy Star models. So buy a unit from a knowledgeable retailer who will help you select the right-sized equipment for your room.

Consumers replacing an existing unit should not immediately throw the old one away. Air conditioners contain a refrigerant that should be removed by a trained technician first. Contact your local solid waste organization for information on how to properly dispose of old air conditioners.

About the Author

Brian Sloboda is a program manager specializing in energy efficiency for the Cooperative Research Network, a service of the National Rural Electric Cooperative Association.